In order to study the development track and hot spot changing trends of blasting technology in openpit mining, 1116 valid journal articles were retrieved as a sample from the China National Knowledge Infrastructure (CNKI) database by selecting “open-pit mining” and “blasting” as the search criteria. According the visual analysis reports from CNKI and utilizing the visual knowledge graph tool CiteSpace, a comprehensive and in-depth study has been conducted on the state of the art, distribution characteristics, research hotspots, and cutting-edge trends in the field of open-pit mining blasting research in China. The research findings indicate that the study of open-pit mining blasting has undergone three distinct stages: the establishment and development of open-pit mining blasting theory (pre—2010), the phase of modern technology application and innovation (2010—2015), and the stage of green, intelligent, and precision development (2015—present). The disciplinary distribution primarily focuses on mining engineering and general industrial technology and equipment. The prominent journals for publication include Blasting, Engineering Blasting, and other journals in the field of mining engineering. The majority of authors and institutions are affiliated with mining-related universities, enterprises and research institutes. The research topics encompass various aspects, including the development and application of blasting design software, optimization of blasting parameters (such as blast hole pattern, powder factor and charge structure), deep-hole blasting, bench blasting, cast blasting, pre-splitting blasting, control and monitoring of blasting vibration, numerical simulation, and application of artificial intelligence algorithms, analysis of factors affecting blasting quality and evaluation of blasting effects. The future of open-pit mining blasting will continue to evolve towards automation, intelligence, precision and environmental friendliness. Through technological innovation and interdisciplinary integration, the industry aims to provide more efficient, safer and sustainable blasting solutions for the mining sector.

It is prone to occur dynamic disasters such as roof falling, sidewall slabbing and rock burst under dynamic disturbance of mechanical percussion drilling and explosive blasting in the roadway with hard rock. It is extremely meaningful to investigate the dynamic load effect on roadway deformation and failure mechanism. To understand the mechanical behavior of roadway surrounding rock under dynamic disturbance, a hard rock roadway was simplified as a hole in rock. And then, a series of impact tests were conducted on prismatic sandstone rock specimens with a hole by a modified split Hopkinson pressure bar testing system to explore the influence of hole size and shape on the dynamic mechanical properties, failure mode and energy dissipation characteristics. The results show that the existence of the hole has significant weakening effects on the dynamic strength, dynamic elastic modulus and peak strain. The dynamic mechanical properties of the rock decrease significantly with the increase of hole size. Among the specimens with different hole shapes, the dynamic strength and peak strain of the square-holed specimens are the largest, followed by the horseshoe-holed and the circle-holed specimens, but their elastic moduli show opposite results. In terms of rock failure modes, splitting tensile and tensile-shear failure occur respectively in intact specimens and pre-holed specimens under impact load. Additionally, the energy consumption density and fractal dimension of the horseshoe-holed specimens are the largest, which are 1.94 J/cm³ and 2.11 J/cm³, respectively. It indicates that the failure process is the most intense for the horseshoe-holed specimens, while the fragmentation degree of the circle and square holed specimens is not much different.

In order to explore the dynamic crack propagation law of beam members, bar defects with the heights of 22 mm, 28.5 mm and 35 mm were designed in a three-point bending beam, and then tested by the digital laser dynamic caustic line experiment system and the drop weight impact test system. The results show that the crack propagation rate and stress intensity factor are affected by the defect height in two stages in the drop weight impact experiment. In the first stage, the maximum growth rates of crack propagation have a trend of first rising and then stabilizing as 247.49 m/s, 292.49 m/s and 284.99 m/s with the increase of defect height, and the cracking stress intensity factor was respectively 1.480 MPa/m^3/2, 1.665 MPa/m^3/2 and 1.812 MPa/m^3/2, which increased with the increase of defect height. Meanwhile, the crack initiation and propagation rates respectively decreased by 634.42 m/s, 524.97 m/s and 377.67 m/s, the cracking stress intensity factors of K_Ⅰ type respectively decreased by 3.281 MPa/m^3/2, 3.192 MPa/m^3/2 and 2.876 MPa/m^3/2, and the cracking stress intensity factors of K_Ⅱ type respectively increased by 1.254 MPa/m^3/2, 1.319 MPa/m^3/2, and 1.398 MPa/m^3/2. Furthermore, the K_Ⅰ-K_Ⅱ composite stress intensity factor was transformed into a K_Ⅰ type stress intensity factor by deflection.

Blasting is widely used in tunnel engineering as a large scale and high efficiency method of rock breakage, but it inevitably brings some bad effects to the adjacent structures and surrounding rocks, among which blasting vibration is the first. Electronic detonator initiation can realize the active control of blasting vibration intensity and spectrum due to its accurate delay, high reliability and safety, which is an effective means to reduce the seismic effect of blasting. In order to explore the influence of the location and number of electronic detonators on the frequency spectrum of blasting vibration, field tests and numerical calculations were combined. The main frequency characteristics of blasting vibration are summarized for five different initiation locations, including the bottom of the charge, the top of the charge, the middle of the charge, simultaneous initiation at the top and bottom of the charge, and simultaneous initiation at two points evenly distributed in the charge section. Based on the spectrum expression of blasting vibration in viscoelastic medium, the characteristics of blasting loads under different working conditions were analyzed from the perspective of superposition of blasting sources, which was used to reveal the influence of detonator arrangement on blasting vibration frequency spectrum. The results show that the initiation conditions are ranked as simultaneous initiation of two uniformly distributed points, middle initiation, simultaneous initiation at the top and bottom, top initiation and bottom initiation, in the order of vibration frequency from largest to smallest. Multiple detonators actually divide the whole charge into several segments, which is equivalent to superposition of multiple sub-explosive sources. Changing the location or number of detonators is essentially to detonate the entire charge in segments at the same time. The more segments, the length of sub-explosive source charge and the detonation process are shorter, which means the energy release rate of explosives and the blasting vibration frequency are higher, and the rise of explosion load is faster. In addition, with the increase of distance to blast source, the influence of detonator position on blasting vibration frequency converges.

Ground blasting vibration control is one of the key contents in the blasting construction of subway tunnels in complex urban environment, and cut blasting is the key to determine the blasting vibration intensity. Combined with the actual project of the north extension line of WuHan Metro Line 7 (Qianchuan Line), an optimization design was carried out on the basis of the original blasting cut method. The numerical simulation and field vibration test verification methods were used to calculate and compare the blasting vibration effects of single wedge cutting, burn cut with four holes and double wedge cutting. Then, the optimization method of cut blasting was proposed. The results show that single wedge cutting, burn cut and double wedge cutting have similar propagation rules of blast vibrations along the axis of tunnel excavation. The peak vibration velocity along the x direction (horizontal radial) decreases with the increase of the distance from the working face in the range of 0~-5 m. When distance exceeds 5 m, the peak vibration velocity increases first and then decreases. The excavated area of the upper bench of the left pilot tunnel has an amplification effect on the surface vibration velocity, which is referred as a “cavity effect”. The distribution of the x-direction (horizontal radial) peak vibration velocity on the left and right sides of the tunnel is roughly similar, and gradually decreases with the increase of the horizontal absolute distance from the origin along the direction perpendicular to the axis of tunnel excavation. The upper bench of the left pilot tunnel has a free face, which makes the peak vibration velocity along the x direction (horizontal radial) on the left side of the tunnel bigger than that on the right side. Due to the delayed initiation, the peak vibration velocity along the x direction (horizontal radial) by double wedge cut blasting is the minimum. The surface vibration velocity of the excavated area is 1.35~2.02 times than that of the unexcavated area ahead during the tunnel blasting construction, due to the “cavity effect”. Compared with other cutting methods, the “cavity effect” of the double wedge cutting is weaker. The comparative analysis of blasting vibration intensity of the three kinds of cutting modes shows that the order of advantages and disadvantages of the three kinds of cutting modes is: double wedge cutting > single wedge cutting > four straight hole cutting.

To study the complex mechanical movement and accumulation process of broken blocks in the process of underwater rock bench blasting, a fluid-solid coupling numerical calculation method based on FLUENT-EDEM was adopted. Firstly, the parallel bond and Hertz-Mindlin contact model were introduced between the particles, and the parameters of the parallel bond were calibrated by comparing the results of Brazilian splitting experiment and numerical calculation. Furthermore, the underwater bench blasting model was established, and the mechanical action mechanism of water on rock mass breaking and movement was analyzed. Finally, the whole ejection process of particles from a submerged step block was studied, and characteristics of the block velocity, block stacking and flow field were discussed. The results show that the accumulation and stratification of block particles are related to their initial velocity and height, and the horizontal movement distance of the block particles in the middle step is the biggest under the explosion load action. Meanwhile, the block particles in the upper blocking part mainly roll and cover the middle block particle layer under the action of gravity and buoyancy, which are less affected by the explosion load. Additionally, the explosion energy is mainly used to break the rock at the initial detonation stage, and the water has no obvious flow velocity. With the bulging and throwing movement of block particles, the fluid streamline velocity near the front surface of the bench is largest. When the block particles start to roll and slide, the streamline is mainly affected by the movement form of the particles. Therefore, the fluid-solid coupling model by Fluent-EDEM can accurately simulate the block motion in the underwater bench blasting, which can provide a new research method for underwater rock blasting engineering.

The authenticity of fracture distribution model is one of the key factors during numerical simulation of blasting in jointed rock mass, which would obviously affect the numerical simulation results. It is hard to represent the complex three-dimensional joint distribution in the existing joint construction method. To explore a simple and feasible operation method for constructing the complex 3D joint model in LS-DYNA software, a K file of blasting numerical model was analyzed and reorganized by MATLAB software. Furthermore, a 3D refined numerical model for jointed rock mass was constructed by the 3D joint distribution law and the constitutive joint model parameters. Finally, a statistical analysis of the three-dimensional joint distribution law was carried out in an open-pit limestone mine, and the joints were reconstructed in the numerical model of a bench blasting. Consequently, a comparative study of the numerical simulation and the field blasting test for open-pit bench blasting was carried out. The results show that the error between the joints built in the numerical model and the actual joints is less than 13%. The joint surface changes the damage distribution of the rock mass. Compared with the intact rock mass, the damage rock mass range increases by 12.04%, and the proportion of fragments with the size of 0~100 mm decreases by 8.11%. The damage results obtained by blasting simulation are close to the field rock breaking effect, and the percentage error of fragments with the size of 0~100 mm is 4.16%. The analytical reconstruction method is feasible and easy to represent the complex three-dimensional joint distribution, and the numerical results are close to experimental results.

In order to better study rock blasting mechanism better in layered rock strata, the dynamic tensile mechanical characteristics of the carboniferous shale surrounding rock mass around the Sujiayan tunnel were explored, which belongs to the north section of the Zhengwan high-speed railway project in western Hubei Province. To reveal the effects of impact angle and velocity on the dynamic tensile strength and corresponding failure mode of carbonaceous shale, dynamic Brazilian splitting tests were carried out under five impact angles (0°, 30°, 45°, 60° and 90°) by the split Hopkinson pressure bar (SHPB) device with a high-speed camera and the digital image correlation technology (DIC). At the same time, different impact velocities for every impact angle were also tested by three impact pressures (0.1 MPa, 0.2 MPa and 0.3 MPa). The results show that the dynamic tensile strength of the shale decreases first and then increases with the increase of impact angle under different impact velocities. The minimum value is reached when the impact angle is 30° and the maximum value is reached when the impact angle is 90°. The dynamic tensile strength of shale presents a significant anisotropy, and the degree of anisotropy decreases with the increase of impact velocity. With the increase of impact velocity, the dynamic tensile strength of shale increases correspondingly, and there is a significant linear relationship between the dynamic tensile strength and impact velocity. In addition, both impact angle and impact velocity have a great influence on the dynamic tensile failure mode of shale.

To explore the mechanical mechanism of burn cut blasting with a large-diameter empty hole, the stress concentration effect of the large-diameter empty hole was studied by theoretical analysis and numerical simulation. Firstly, a mechanical model for the stress concentration effect of the empty hole was established. Furthermore, the empty hole's stress concentration effect was clarified based on the elasticity theory and wave dynamics. A numerical simulation under a typical working condition was then carried out, and finally the stress concentration effect of the empty hole was investigated based on the numerical results of stress wave propagation, rock damage, and the first principal stress. The results show that the stress concentration effect of the empty hole is mainly derived from the stress concentration around the cavity and the stress wave superposition effect. During the blasting process, the stress wave is reflected at the empty hole wall and superposed with the incident wave, which is mostly located in the vicinity of the empty hole and the region between the cut holes. The regions with high damage degree are mainly around the cut hole, near the empty hole, and within the triangle regions formed by adjacent cut holes and the empty hole, and the latter two regions correspond to the stress wave superposition regions. There is a significant stress concentration effect near the empty hole, and the closer the rock is to the empty hole, the more obvious the effect is.

In order to improve the quality of tunnel blasting and reduce the disturbance to surrounding rock during blasting construction, it is necessary to carry out optimization research on the original blasting scheme. Taking the parallel guide tunnel of a railway project as the engineering background, more reasonable blasting parameters are determined by using the empirical formula to calculate the powder factor, the number of holes and the parameters of each hole, aiming at the problems such as serious over-under excavation, poor working environment and slow construction progress. The number of medium and large diameter empty holes in the original blasting scheme is changed from 8 to 2, and the layout of cut holes is adjusted to provide better free surface for subsequent holes. At the same time, the orifice of the charging structure is blocked by water bags, which reduces the concentration of dust and harmful gases in the tunnel after explosion. The results show that the average linear over excavation can be reduced from 0.2~0.4 m to 0.15 m with smooth working face and bottom by using the optimized blasting scheme. At the same time, compared with the original scheme, the number of holes and the amount of explosives used in each cycle can be reduced by 37 and 49.2 kg, respectively. In addition, the construction time can be saved by 1.1 h and the cost is about 800 yuan, which has a relatively significant technical effect and economic value, and also verifies the feasibility of the optimized blasting scheme.